Water disinfection using UV irradiation has emerged in the past years as a good alternative due to growing concerns with chlorinated by-products and safety of measuring chlorination. It is known that the performance of UV reactors is determined by distribution of UV dose, defined as the product of hydraulic residence time and light irradiance intensity. However, information for hydraulic residence time for evaluating hydraulic performance of UV reactors are limited. In this project a real time 2D digital particle image velocimetry is used to measure velocity distribution in two UV reactors, UV-SWIFT and UV-MAX. Turbulence, Reynolds stresses, dissipation, and vorticity at the regions of the wall of the reactor and the near-far fields of the UV lamps are characterized for the purpose of calibrating and verifying the models of UV reactors. We are currently working on characterization of mixing and 3D turbulent motions using laser-induced flow visualization and 3D particle image velocimetery. In addition, a flunet CFD software is used to examine irradiation efficicay of UV disinfection process
Raw
image
Velocity and
Vorticity
UV-MAX
Excessive growths of
blue-green algae (cyanobacteria) are a common problem in
eutrophic (fertile) lakes world-wide. Many blue-green
algae species (including non-scum formers) can also
produce hepato- or neuro-toxins of health concern to
humans and other warm-blooded animals. Thus, beaches and
swimming areas on certain shorelines can periodically
experience large densities of blue-green algae that are
not only unaesthetic, but potentially harmful to human
health. In collaboration with City of Madison, Dane
County, and Department of Natural Resources, we have
tested a variety of devices, called algal scum
interceptor, deflector, and exclosure (ASIDE)
system, to reduce the presence of algal scums at several
public beaches. One of the effective devices is an
enclosure at Brittingham Beach and Bernie Beach, Monona
Bay. The exclosure consists of a flotation collar and full
water depth curtain. The full water depth curtain provides
a mean to separate the lake water from the inside beach
water as to exclude unsafe lake water from contaminating
the swimming area. Furthermore, a treatment system is used
to pump water inside the swimming area which filters and
disinfects beach water using a series sand filter and UV
system. The clean, treated water is then returned to the
swimming area while algae and other unwanted materials are
backwashed based on system pressures to the sanitary
sewer. To provide real-time information and test its
effectiveness, a Real
Time Water Imaging System (RTWIS) is currently
developed.
